%0 Journal Article
%T Preventive and curative effect of melatonin on mammary carcinogenesis induced by dimethylbenz[a]anthracene in the female Sprague¨CDawley rat
%A V¨¦ronique Lenoir
%A Marianne Yon de Jonage-Canonico
%A Marie-H¨¦l¨¨ne Perrin
%A Antoine Martin
%A Robert Scholler
%A Bernard Kerdelhu¨¦
%J Breast Cancer Research
%D 2005
%I BioMed Central
%R 10.1186/bcr1031
%X The aim of this study was to compare the potency of melatonin to limit the frequency of mammary cancer initiation with its potency to inhibit tumor progression once initiation, at 55 days of age, was achieved. The present study compared the effect of preventive treatment with melatonin (10 mg/kg daily) administered for only 15 days before the administration of DMBA with the effect of long-term (6-month) curative treatment with the same dose of melatonin starting the day after DMBA administration. The rats were followed up for a year after the administration of the DMBA.The results clearly showed almost identical preventive and curative effects of melatonin on the growth of DMBA-induced mammary ADK. Many hypotheses have been proposed to explain the inhibitory effects of melatonin. However, the mechanisms responsible for its strong preventive effect are still a matter of debate. At least, it can be envisaged that the artificial amplification of the intensity of the circadian rhythm of melatonin could markedly reduce the DNA damage provoked by DMBA and therefore the frequency of cancer initiation.In view of the present results, obtained in the female Sprague¨CDawley rat, it can be envisaged that the long-term inhibition of mammary ADK promotion by a brief, preventive treatment with melatonin could also reduce the risk of breast cancer induced in women by unidentified environmental factors.It has been well documented that the pineal hormone, melatonin, besides its well established circadian rhythm, plays a major role in the control of reproduction in mammals [1,2]. The role of the pineal gland, the major source of melatonin, in the development of breast [3] and mammary [4,5] cancer has been clearly documented. Also, it has been shown that melatonin may exert in vivo [6,7] and in vitro [8-10] an oncostatic activity by at least a direct action on the mammary tissue [11] and on the activation of estrogen receptor (ER) for DNA binding [12], or by modulation of the expression
%U http://breast-cancer-research.com/content/7/4/R470